In recent years, with the rapid development of computer and communication technologies, the extensive use of computers and computer networks has become possible. Thus, public organizations, companies or the like use not only internal networks but also external networks such as the Internet to manage business related information or the like and transmit files or the like to the inside or outside.
However, since the external networks such as the Internet are vulnerable to external attacks, public organizations and companies deploy and operate supplementary firewalls to secure important internal information. Although the firewalls are installed, it is impossible to completely protect important internal information against intentional external attacks because they cannot prevent accesses which bypass them.
Thus, recently, a network separation technology has been introduced that separates an internal network and an external network from each other, thereby attempting to protect important internal information against attacks made over the external network.
The network separation technology refers to a technology that organizes two or more networks that have been separated for the purpose and prevents network packet data from being transferred between the networks. Therefore, the network separation technology prevents one network from being damaged even when the other network has been infiltrated by hacking or the like. The prior art related to the network separation technology is disclosed in Korean Unexamined Patent Publication No. 2007-111603 (published on Nov. 22, 2007).
The network separation technique described above may include logically separating a server that stores important information, from among a plurality of servers existing in the same internal network, as if it exists in a different network, and puts in practice the separated server.
However, most of network separation techniques are merely related to methods for selectively restricting a client terminal from accessing a server through authentication in a network in which the client terminal and the server coexist, rather than related to a concept of separating the server from a particular network.
With such conventional methods, a method for authenticating the client by the server needs to be provided and the client requires of creating authentication information. Thus, the conventional methods may not be globally applied to general clients and a general server.